The present invention relates to high field open magnet devices and, more particularly, to systems for minimizing magnet motion and reducing the risk of image phase ghosting of such devices.
High field open (HFO) magnets utilize super-conducting magnet technology to generate magnetic fields. The HFO magnets are particularly used in magnetic resonant imaging (MRI), diagnostic systems in order to diagnose and/or evaluate various conditions in humans. The HFO magnet essentially rotates a cylindrical magnet to a vertical position. This causes a relatively high center of gravity for the magnet leading to problems of adequately securing the HFO device to the ground. Magnetically unstable magnets can produce image phase ghosting and other high magnetic field variations.
There is thus a need for a secure anchoring system for HFO magnets in order to prevent magnet wobbling. There also is a need to securely fasten the HFO magnet to a supporting surface and at the same time maintain RF screen room integrity.
The present invention provides a system for connecting an HFO magnet device to the ground or other surface and at the same time maintain RF screen room integrity. A large metal plate member is utilized for this purpose, with metal angle members attached around its perimeter in order to maintain requisite RF shield contact and integrity. Preferably, a two inch thick 72-inch by 72-inch stainless steel plate member is utilized. The plate is permanently mounted to the floor or other surface and the HFO device is securely bolted to the metal plate member. This provides the mechanical stability needed for minimizing magnet motion.
A plurality of holes and openings are provided in the plate member, some for connecting the plate to the floor or other surface and others for connecting the HFO magnet device to the plate. The holes for connecting the HFO device to the plate are drilled and tapped for the use of bolts or other fasteners. A plurality of bolts and washers are used to connect the HFO magnet device to the plate and the plate to the floor or other surface. For uneven floors or other surfaces, epoxy, grout or other xe2x80x9cmudxe2x80x9d is utilized to provide a firm and flat foundation. Standard expansion anchor bolts are utilized to connect the metal plate member to the floor or other surface.
The metal angle members preferably are welded to the four edges of the plate and provide a solid connector to the RF shield room. Brass wool or other RF sealing material is positioned between the angle members and the floor of the RF shield room which normally is covered with a sheet of copper material.